linux/drivers/base/core.c, branch v5.6

driver core: Skip unnecessary work when device doesn't have sync_state()

2020-03-04T12:46:03Z

A bunch of busy work is done for devices that don't have sync_state() support. Stop doing the busy work. Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20200221080510.197337-4-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

driver core: Call sync_state() even if supplier has no consumers

2020-03-04T12:46:03Z

The initial patch that added sync_state() support didn't handle the case where a supplier has no consumers. This was because when a device is successfully bound with a driver, only its suppliers were checked to see if they are eligible to get a sync_state(). This is not sufficient for devices that have no consumers but still need to do device state clean up. So fix this. Fixes: fc5a251d0fd7ca90 (driver core: Add sync_state driver/bus callback) Signed-off-by: Saravana Kannan Cc: stable Link: https://lore.kernel.org/r/20200221080510.197337-2-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

driver core: Allow device link operations inside sync_state()

2019-11-15T02:06:54Z

Some sync_state() implementations might need to call APIs that in turn make calls to device link APIs. So, do the sync_state() callbacks without holding the device link lock. Signed-off-by: Saravana Kannan Reviewed-by: Rafael J. Wysocki Link: https://lore.kernel.org/r/20191114225646.251277-1-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

driver core: Allow fwnode_operations.add_links to differentiate errors

2019-11-02T17:05:18Z

When add_links() still has suppliers that it needs to link to in the future, this patch allows it to differentiate between suppliers that are needed for probing vs suppliers that are needed for sync_state() correctness. Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20191028220027.251605-4-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

driver core: Allow a device to wait on optional suppliers

2019-11-02T17:05:17Z

Before this change, if a device is waiting on suppliers, it's assumed that all those suppliers are needed for the device to probe successfully. This change allows marking a devices as waiting only on optional suppliers. This allows a device to wait on suppliers (and link to them as soon as they are available) without preventing the device from being probed. Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20191028220027.251605-3-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

driver core: Add device link support for SYNC_STATE_ONLY flag

2019-11-02T17:05:17Z

Parent devices might need to create "proxy" device links from themselves to supplier devices to make sure the supplier devices don't get a sync_state() before the child consumer devices get a chance to add device links to the supplier devices. However, the parent device has no real dependency on the supplier device and probing, suspend/resume or runtime PM don't need to be affected by the supplier device. To capture these cases, create a SYNC_STATE_ONLY device link flag that only affects sync_state() behavior and doesn't affect probing, suspend/resume or runtime PM. Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20191028220027.251605-2-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

Merge 5.4-rc5 into driver-core-next

2019-10-27T17:54:13Z

We want the sysfs fix in here as well to build on top of. Signed-off-by: Greg Kroah-Hartman

cpufreq: Avoid cpufreq_suspend() deadlock on system shutdown

2019-10-10T09:11:17Z

It is incorrect to set the cpufreq syscore shutdown callback pointer to cpufreq_suspend(), because that function cannot be run in the syscore stage of system shutdown for two reasons: (a) it may attempt to carry out actions depending on devices that have already been shut down at that point and (b) the RCU synchronization carried out by it may not be able to make progress then. The latter issue has been present since commit 45975c7d21a1 ("rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds"), but the former one has been there since commit 90de2a4aa9f3 ("cpufreq: suspend cpufreq governors on shutdown") regardless. Fix that by dropping cpufreq_syscore_ops altogether and making device_shutdown() call cpufreq_suspend() directly before shutting down devices, which is along the lines of what system-wide power management does. Fixes: 45975c7d21a1 ("rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds") Fixes: 90de2a4aa9f3 ("cpufreq: suspend cpufreq governors on shutdown") Reported-by: Ville Syrjälä Tested-by: Ville Syrjälä Signed-off-by: Rafael J. Wysocki Acked-by: Viresh Kumar Cc: 4.0+ # 4.0+

driver core: Add sync_state driver/bus callback

2019-10-04T15:30:19Z

This sync_state driver/bus callback is called once all the consumers of a supplier have probed successfully. This allows the supplier device's driver/bus to sync the supplier device's state to the software state with the guarantee that all the consumers are actively managing the resources provided by the supplier device. To maintain backwards compatibility and ease transition from existing frameworks and resource cleanup schemes, late_initcall_sync is the earliest when the sync_state callback might be called. There is no upper bound on the time by which the sync_state callback has to be called. This is because if a consumer device never probes, the supplier has to maintain its resources in the state left by the bootloader. For example, if the bootloader leaves the display backlight at a fixed voltage and the backlight driver is never probed, you don't want the backlight to ever be turned off after boot up. Also, when multiple devices are added after kernel init, some suppliers could be added before their consumer devices get added. In these instances, the supplier devices could get their sync_state callback called right after they probe because the consumers devices haven't had a chance to create device links to the suppliers. To handle this correctly, this change also provides APIs to pause/resume sync state callbacks so that when multiple devices are added, their sync_state callback evaluation can be postponed to happen after all of them are added. kbuild test robot reported missing documentation for device.state_synced Reported-by: kbuild test robot Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20190904211126.47518-5-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

driver core: Add support for linking devices during device addition

2019-10-04T15:29:50Z

The firmware corresponding to a device (dev.fwnode) might be able to provide functional dependency information between a device and its supplier and consumer devices. Tracking this functional dependency allows optimizing device probe order and informing a supplier when all its consumers have probed (and thereby actively managing their resources). The existing device links feature allows tracking and using supplier-consumer relationships. So, this patch adds the add_links() fwnode callback to allow firmware to create device links for each device as the device is added. However, when consumer devices are added, they might not have a supplier device to link to despite needing mandatory resources/functionality from one or more suppliers. A waiting_for_suppliers list is created to track such consumers and retry linking them when new devices get added. Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20190904211126.47518-3-saravanak@google.com Signed-off-by: Greg Kroah-Hartman